1/2/3: No access to preferred seating, a friendly agent might grant access but YMMV. Have had some luck asking in the Lounge and at the Gate when flights are not full.
5: Yes to AC Maple Leaf Lounge access and other *A lounges, including on domestic.
6: Yes to early boarding as *G, typically Zone 2 via the priority lane
4: No impact on any of the above